Light emitting devices, such as Light Emitting Diodes (LEDs) or Laser Diodes (LDs), which use group III-V or group II-VI compound semiconductors, are capable of emitting light of various colors, such as red, green and blue, ultraviolet light and the like, owing to developments of device materials and thin film growth technologies. Moreover, these light emitting devices are capable of emitting white light with high efficiency through use of a fluorescent substance or color combination, and have advantages of low power consumption, semi-permanent lifespan, fast response time, safety and environmental friendliness as compared to conventional light sources, such as fluorescent lamps, incandescent lamps and the like.
Accordingly, application sectors of light emitting devices are expanded up to transmitting modules of optical communication means, LED backlights to replace Cold Cathode Fluorescence Lamps (CCFLs) which serve as backlights of Liquid Crystal Display (LCD) apparatuses, white LED lighting apparatuses to replace fluorescent lamps or incandescent lamps, head lights of vehicles and traffic lights.
A light emitting device includes a light emitting structure including a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer sequentially stacked on a substrate formed of sapphire or the like, and a first electrode and a second electrode are respectively disposed on the first conductive semiconductor layer and the second conductive semiconductor layer.
A light emitting device package includes a first electrode and a second electrode disposed on the top of a package body and a light emitting device disposed on the bottom of the package body, the first electrode and the second electrode being electrically connected to each other.
FIGS. 1A and 1B are views showing conventional light emitting device packages.
In case of a light emitting device package 100 provided with a plurality of light emitting devices 150a, 150b and 150c, the light emitting devices 150a, 150b and 150c are arranged on a substrate 110 and spaced apart from one another by a prescribed distance. The light emitting devices 150a, 150b and 150c may emit light of the same wavelength range or light of different wavelength ranges.
For example, when attempting to white light from a light emitting device package, as exemplarily shown in FIG. 1A, three light emitting devices 150a, 150b and 150c to emit red, green and blue light of different wavelength ranges respectively may be arranged on a single substrate 110. Alternatively, the three light emitting devices 150a, 150b and 150c to emit red, green and blue light of different wavelength ranges may be arranged respectively on different substrates 110.
In this case, the three light emitting devices 150a, 150b and 150c may emit light of different wavelength ranges from active layers thereof, or may include different kinds of fluorescent substances disposed on the active layers that emit light of the same wavelength range.
When a plurality of light emitting devices to emit light of different wavelength ranges is used in a single light emitting device package as described above, design limits and increase in cost may be expected.
In particular, in case of rear lighting devices for vehicles that are adapted to emit light of various colors in various shapes within a narrow space, there may be technical limits with regard to close arrangement of light emitting devices to emit light of different wavelength ranges.
FIG. 2A is a view showing a conventional light emitting device package.
In case of a light emitting device package 100 provided with a plurality of light emitting devices 150, the light emitting devices 150 are arranged on a substrate 110 and spaced apart from one another by a prescribed distance. The respective light emitting devices 150 may emit light of the same wavelength range or light of different wavelength ranges.
FIG. 2B is a view showing a conventional light source module.
In the shown light source module, a lens 180 may be located in front of the light emitting device package 100 and serve to change a progress path of light emitted from the respective light emitting devices 150. In particular, when used in lighting devices for vehicles, the lens 180 may be an aspheric lens that directly transmits light from the light emitting devices 150 and, thus, the shape of light sources of the light emitting devices 150 may be important.
However, light sources of light emitting devices typically have a rectangular or square shape and are limited in the emission shape of light to be transmitted outward. In addition, there may be technical limits with regard to close arrangement of respective light emitting devices.